support/download: print command used for download

support/download: print command used for download

Even though that most download commands actually print some output, like
progress indication or other messages, the actual command used is not. This
makes it hard to analyze a build log when you are not fully familiar with
the typical output of said log.

Update the download helpers to do just that, respecting any quiet/verbose
flag so that a silent make (make -s) does not get more verbose.

Note: getting rid of the duplication of the command in the script is not
straightforward without breaking support for arguments with spaces.

Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
[yann.morin.1998@free.fr: use printf, not echo]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>